Modular compact pump

ABSTRACT

The present invention relates to a modularized pump. The pump has end lids  12, 13  with an inlet and an outlet for pumped fluid, and at least two pump modules  7  sandwiched between the end lids  12,13 . Each pump module includes a casing  1  with an enclosed volume  20  and at least two pump stages  6 . At least one coolant inlet  10  and outlet and a separate power connection  16  for connection to a VSD is included in each module. Each pump stage  6  includes an impeller  5  with a rotor  4 , a stator  2  surrounding the rotor  4 , provided to drive the rotor and a can  3  between the impeller  5  and the stator  2.

The present invention relates to a Modular Compact Pump (MCP). MCPs are typically subsea multi-phase pumps. The MCP of the invention is modular and scalable and provides an all-electric boosting system that can accelerate and improve oil recovery in both new and mature wells by adding energy to multi-phase hydrocarbon well-streams and by lowering wellhead pressure. The MCP has integrated motor impellers that rotate around a static shaft. This reduces rotodynamic issues.

The present invention is a modularized pump with an inlet side end lid with a process fluid inlet and an outlet side end lid with a process fluid outlet and at least two pump modules sandwiched between the inlet side end lid and the outlet side end lid. Each pump module includes a casing, an enclosed volume inside the casing, at least two pump stages, at least one coolant inlet, at least one coolant outlet and a separate power connection for connection to a variable speed drive (VSD). Each pump stage includes an impeller with a rotor and a stator surrounding the rotor, provided to drive the rotor. A can is provided to form a barrier and seal between the impeller and the stator.

Each module may include a pressure compensator limiting a pressure difference over the can between a pumped media in an impeller side of the modularized pump and a dielectric fluid inside the casing.

The at least one coolant inlet and the at least one coolant outlet may be in fluid communication with spiral shaped coolant channels surrounding each stator.

The modularized pump may further include metal to metal face seals between the at least two modules.

The pump may further include a polymeric face seal between the at least two modules.

Each module may include two stages.

Short description of the enclosed figure:

FIG. 1 is a cross section of a modularized pump of an embodiment of the invention.

Detailed description of an embodiment of the invention with reference to the enclose figure:

FIG. 1 is a cross-section of a modularized multi-stage, multi-phase, pump with four pump stages 6 and two modules 7. A pump is typically a 2-4-6-8-10-12-stage pump. The configuration does not limit the number of modules that can be stacked as each module includes everything required to operate the module (as opposed to modules driven by a common motor). A set including a Stator-Rotor-Impeller is called a stage. Each module 7 includes two stages 6. An inlet side end lid 12 includes an inlet 14 with a process fluid connection and outlet side end lid 13 includes an outlet 15 with a process fluid connection. Each module 7 includes one or several separate coolant inlets 10 in fluid communication with spiral shaped coolant channels 11, and a separate power connection 16 for connection to a VSD. Each stage is powered and controlled by its own VSD. The modules 7 are thus only connected by one or several ports in relation to the pumped media or process fluid. The separate power connection 16 is typically a 6 pin penetrator, supplying power for two, three phase power systems.

The connections between the modules 7 form metal to metal face seals 18. A separate annular seal 8 surrounds the one or several ports. A rotor 4 and impeller 5 assembly is located within a ceramic cylinder or “can” 3 forming a barrier between the pumped media and dielectric fluid inside a casing 1. The casing 1 form both a stator housing and a pressure vessel separating the process pressure from an ambient seawater pressure. The ceramic cylinder or can 3 is preferably of a non-magnetic or non-electrically conducting material.

A pressure compensator 19 ensures that the pressure difference between the pumped media and the dielectric fluid inside the casing 1, surrounding the stator, is kept within certain limits to ensure low leakage and that the mechanical load on the ceramic cans 3 are kept within design specifications. A communication channel extends from the process side or the pumped fluid side to one side of the pressure compensator 19. The other side of the pressure compensator 19 has a communication channel to the dielectric fluid surrounding the stator 2. The position of the process channel input, ensures a slight overpressure from the outside across the cylindrical ceramic can 3. This can be facilitated by a mechanical spring in the pressure compensator 19.

A stator 2 in a closed volume 17 inside the casing 1 surrounds each rotor 4. The spiral shaped coolant channels 11 surrounds each stator. An internal surface of the casing along with an external surface of an internal cylinder insert, form the spiral shaped coolant channels 11 as a helical path surrounding the stator. An external cooling pump (not shown) circulates cooling fluid, removing heat from the stator. Axial channels in the casing 1 also allow natural convection of the dielectric oil surrounding stator 2 to further improve heat transfer from hot to cold volumes. Each stator has its' coolant fluid inlet port through the casing 1. The two stators 2 in a module 7 has a common cooling fluid outlet port through the casing 1.

Each ceramic can 3 is located between a stator 2 and a rotor 4. The ceramic cans 3 seals the closed volume 17 from the process fluid while allowing the stator to drive the rotor. Stud bolts 9 hold the inlet end lid 12, the outlet end lid 13 and the modules together. The stud bolts 9 and the overall design of the pump simplifies alteration of the number of modules in a pump to accommodate various power requirements and needs.

The impellers 5 of the stages 6 have thus a common central axis and rotates around a static centre portion of the pump. The process fluid flows in an annular channel surrounding the centre. Each module 7 has a plane contact surface perpendicular to the central axis for contact with a neighboring module or an end lid 12, 13. The plane contact surface forms a metal face seal.

The stators 2 include windings and the rotors 4 include fixed magnets. The outer surface of the rotors 4, the cans 3 and the inner surface of the stator are cylindrical. Each impeller 5 is thus driven by the rotor 4 along the perimeter of the impeller. 

1. A modularized pump comprising an inlet side end lid with a process fluid inlet and an outlet side end lid with a process fluid outlet and at least two pump modules sandwiched between the inlet side end lid and the outlet side end lid, each pump module including a casing, an enclosed volume inside said casing, at least one pump stage, at least one coolant inlet, at least one coolant outlet and a separate power connection for connection to a VSD; and wherein each pump stage includes an impeller with a rotor, a stator surrounding the rotor, and a can between the impeller and the stator.
 2. The modularized pump of claim 1, wherein each module includes a pressure compensator limiting a pressure difference over the can between a pumped media in an impeller side of the modularized pump and a dielectric fluid inside the casing.
 3. The modularized pump of claim 1, wherein the at least one coolant inlet, and the at least one coolant outlet are in fluid communication with spiral shaped coolant channels surrounding each stator.
 4. The modularized pump of claim 1, further including a metal to metal face seal between the at least two modules.
 5. The modularized pump of claim 1, further including a polymeric face seal between the at least two modules.
 6. The modularized pump of claim 1, wherein each module includes two stages. 